Has it really been 40 years? Yes, the movie The Exorcist was released the day after Christmas in 1973. I can imagine that really brought people back down to earth after a jolly holiday. To celebrate the anniversary of the movie that brought horror to a new level, mental_floss has posted a list of fun facts about The Exorcist. Here's a taste:

3. THE NAME OF THE DEMON IS PAZUZU.

Though it’s never stated in the film, the demon that takes possession of Regan MacNeil has a name: Pazuzu, which is taken from the name of the king of the demons in Assyrian and Babylonian mythology.

4. MERCEDES MCCAMBRIDGE PROVIDED THE VOICE OF THE DEMON.

The woman Orson Welles once dubbed “the world’s greatest living radio actress” was hired to provide the voice for Linda Blair’s most demonic moments, a decision that became the source of much controversy when McCambridge was not credited for her performance. Some say that this decision was solely McCambridge’s, who claimed that she didn’t want to take away from Blair’s performance, then later changed her mind. Under the threat of legal action, her name was quickly added to the credits.